1. Field of the Invention
The present invention relates to a sputter apparatus, a control device for the sputter apparatus, and a film formation method, and more specifically relates to a sputter apparatus, a control device for the sputter apparatus, and a film formation method to be used to deposit a material on a substrate.
2. Description of the Related Art
Sputtering (hereinafter also referred to as sputter) is widely used as a thin-film formation method. In the case of sputter, a thin film deposited on a substrate to be processed generally has a film thickness distribution in the substrate surface. The following method has been known as a method of improving the film thickness distribution (see Japanese Patent Application Laid-Open No. 2001-240965).
In the method disclosed in Japanese Patent Application Laid-Open No. 2001-240965, the sputter is started using a target placed diagonally opposed to the substrate. Firstly, a deposition rate on the rotating substrate during the sputter is calculated, and a deposition time is calculated based on the deposition rate and a film thickness to be obtained. Then, a rotation speed of the substrate is controlled so that the substrate can rotate an integer multiple of times within the deposition time (that is, a deposition start angle and a deposition end angle of the substrate are set to be the same). It is disclosed that this control cancels out the unevenness in the film thickness in the substrate surface, and thereby improves the film thickness distribution.
In general, however, the deposition rate varies by a certain amount at the sputter starts, and requires a certain period of time is needed to stabilize the deposition rate. For this reason, even though the method as described in Japanese Patent Application Laid-Open No. 2001-240965 is performed, the thin film thus deposited has a film thickness distribution in the substrate surface.